[Android WebView] Call shouldInterceptRequest on a background thread

android_webview/java/src/org/chromium/android_webview/AwContentsBackgroundThreadClient.java

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.android_webview;
+
+import org.chromium.base.annotations.CalledByNative;
+import org.chromium.base.annotations.JNINamespace;
+
+import java.util.HashMap;
+
+/**
+ * Delegate for handling callbacks. All methods are called on the background thread.
+ * "Background" means something that isn't UI or IO.
+ */
+@JNINamespace("android_webview")
+public abstract class AwContentsBackgroundThreadClient {
+
+    public abstract AwWebResourceResponse shouldInterceptRequest(
+            AwContentsClient.AwWebResourceRequest request);
+
+    // Protected methods ---------------------------------------------------------------------------
+
+    @CalledByNative
+    private AwWebResourceResponse shouldInterceptRequestFromNative(String url, boolean isMainFrame,
+            boolean hasUserGesture, String method, String[] requestHeaderNames,
+            String[] requestHeaderValues) {
+        AwContentsClient.AwWebResourceRequest request =
+                new AwContentsClient.AwWebResourceRequest();
+        request.url = url;
+        request.isMainFrame = isMainFrame;
+        request.hasUserGesture = hasUserGesture;
+        request.method = method;
+        request.requestHeaders = new HashMap<String, String>(requestHeaderNames.length);
+        for (int i = 0; i < requestHeaderNames.length; ++i) {
+            request.requestHeaders.put(requestHeaderNames[i], requestHeaderValues[i]);
+        }
+        return shouldInterceptRequest(request);
+    }
+}